Magnetization process in a classical system of Preisach-type particles

Abstract

The magnetization process of a regular two-dimensional array of small individual, strongly uniaxial magnetic garnet particles, groups of particles and major loop properties of a “macroscopic” sample has been investigated experimentally in an optical magnetometer. These particles correspond to the assumptions of a simple Preisach model. The switching mode is coherent rotation. Each particle has a square hysteresis loop, with no reversible or apparent reversible component. Requirements of wiping-out and congruency properties are satisfied. From measurements of the up- and down switching field on individual particles, the major loop can be reconstructed, and it is shown to be in nearly exact correspondence with the measured one. The transition from individual to collective behavior is smooth and the properties of a system consisting of 100 particles correspond to the major loop behavior. The interaction field for an assembly of 25 particles was calculated numerically. The switching sequence and the magnetization curve for the 25 particles assembly was derived from the calculated interaction fields and found to be in a very good agreement with the measured values.